Lifespan development examines patterns of growth, change, and stability from conception to death. It takes a scientific, developmental approach and recognizes that both heredity and environment influence development. There are three major areas of study: physical, cognitive, and social/personality development. Several theoretical perspectives aim to explain lifespan development, including psychodynamic, behavioral, cognitive, humanistic, contextual, and evolutionary theories. Theories are tested through scientific research methods like experiments and correlations to determine causes, relationships, and changes over time.